Voltage indicator arrangement for electrostatic precipitators



VOLTAGE INDICATOR ARRANGEMENT FOR ELECTROSTATIC PRECIPITATORS Filed Nov. 29, 1963 INVENTOR. GILBERT H. JOHNSON ("W 523 AT TOR N EY United States Patent 3,266,222 VOLTAGE INDICATOR ARRANGEMENT FOR ELECTROSTATIC PRECIPITATORS Gilbert H. Johnson, Louisville, Ky., assignor to American Air Filter Company, Inc., Louisville, Ky., a corporation of Delaware Filed Nov. 29, 1963, Ser. No. 327,036 1 Claim. (Cl. 55-104) The present invention relates to electrostatic precipitators and more particularly to an improved load indicator arrangement for indicating a preselected voltage range delivered to electrostatic precipitators.

Voltage indicator arrangements for gas cleaning electrostatic precipitators are well known in the art, such arrangements usually including an electric light adapted to glow when an appropriate amount of voltage is delivered to a precipitator for operational purposes and to turn off when the voltage falls below a preselected level. For the most part, these past arrangements have been limited in operational scope and frequently have been misleading as a result of their sensitivity of response to short-lived voltage surges common in precipitating operations. Although a number of attempts have been made to eliminate the aforementioned difficulties, such attempts have proven to be complex and costly and have not always been successful.

The present invention provides a straightforward, economical and easy to maintain voltage indicator arrangement for an electrostatic precipitator which recognizes and eliminates the aforementioned problems of the past, providing accurate indicating operations utilizable over a wide range of variable gas cleaning conditions and eliminating misleading frequent on-01f flashing of the glow lamp as has been known in the past.

Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosures set forth herein.

More particularly, the present invention provides, in an electrostatic precipitator arrangement for cleaning a dirty gas stream, an improved load indicator for indicating that a preselected maximum-minimum voltage range is being delivered to the precipitator comprising: means for delivering a high voltage to delivering a low voltage to the load indicator; a first relay means responsive to operate at a preselected high voltage range as it is delivered to the precipitator; and, a second relay means responsive to operate upon a preselected time delay after operation of the first relay means, the operation of the second relay means causing operation of a load indicator. In addition, the present invention provides a regulating means to regulate cut-out or the low point of operation of the first relay means, without altering cut-in or the high point of operation of the first relay means, the regulating means being responsive to operation of the second relay means which operates the load indicator.

It is to be understood that various changes can be made in the arrangement, form and construction of the apparatus set forth herein without departing from the scope or spirit of the present invention.

The invention will now be described with reference to the drawing which discloses circuitry schematic of one advantageous embodiment of the present invention.

As can be seen in the drawing, connected across high voltage line T1-T2, which receives its power from a secondary winding of a transformer (not shown), is electrostatic precipitator 2. Also connected across line T1-T2 is relay R1, this relay having resistor RS in series therewith. Relay Rl, which can be selected from any one of a number of known relays, advantageously is of a magnetic type because of the low current to be delivered the precipitator; means for thereto. For example, a magnetic relay of a type manufactured by the Kurman Electric Co., Brooklyn, NY. can be used. Relay R1 has a preselected operating range between its high or cut-in point and its low or cutout point, the range of this relay and the resistor RS being selected in accordance with the voltage to be delivered to line Tl-TZ. Shunting relay R1 is potentiom-eter or variable resistor assembly 3, this assembly including an adjusting arm 4 having normally open switch RZC disposed in series therewith.

Switch R2C in potentiometer assembly 3 is arranged to be responsive to energization of relay R2 connected across low voltage circuit L1L2. Relay R2 in low voltage circuit Ll-LZ is arranged in series with normally open switch RIC which is responsive to energization of relay R1, aforedescribed in high voltage circuit Tic-T2. Advantageously, relay R2 is of a time delay type, operating a preselected time after switch RIC has been closed by relay R1 and thus avoiding misleading responses to frequent and short-lived voltage surges common in electrostatic precipitator operations. For example, a relay of five seconds time delay, such as a N05, made by Amperite Company, Inc., New York, N.Y., can be used. It is to be noted that also connected across low voltage line Ll-LZ is a suitable glow light 6. Glow light 6 has connected in series therewith normally open switch R2C responsive to be closed upon energization of relay R2.

In a typical operation of the system aforedescribed, when the voltage across line T1-T2 reaches a certain preselected level, relay R1 is energized or cuts-in to close normally open switch RIC in low voltage circuit L1-L2. Shortly thereafter (for example, five seconds) relay R2 is energized, this relay serving to close the pair of switches RZC, one of which is in series with light 6 and the other of which is in series with potentiometer arm 4. With the closing of these two switches, light 6 glows and the low level point of relay R1, as determined by positioning of potentiometer arm 4, is established. Once the voltage reaches the low level point established by potentiometer arm 4, relay R1 cuts-out or is deenergized, opening switch RIC and causing relay R2 to be de-energized to cause light 6 to be extinguished and potentiometer arm switch RZC to be open.

Thus, it can be seen from the aforedescribed circuit that an economical and straightforward arrangement is provided which allows accurate operation over a wide range of operating conditions by merely adjusting potentiometer 4 in accordance with the conditions and which, at the same time, eliminates on-off flashing of the glow light.

The invention claimed is:

In an electrostatic precipitator arrangement for cleaning a dirty gas stream, an improved load indicator arrangement for indicating that a preselected. maximumminimum voltage range is being delivered to said precipitator comprising:

(a) a first circuit for delivering a high voltage to said precipitator connected thereacross;

(b) a second circuit for delivering a low voltage to said load indicator connected thereacross;

(c) a first relay member with a resistor in series therewith connected across said first circuit, said first relay member being responsive to operate at a preselected voltage range upon reaching a preselected voltage level across said first circuit;

(d) an adjustable variable resistor circuit shunting said first relay member to adjust the minimum voltage of the preselected maximum-minimum voltage range of said first relay member;

(e) a second relay member connected across said second circuit, said second relay member being a time delay relay;

(f) a first switching means in said second circuit responsive to the operation of said first relay member of said first circuit to cause said second relay member to operate after a preselected time period;

(g) a second switching means in said second circuit responsive to the operation of said second relay member to operate said load indicator; and,

(h) a third switching means in said variable resistor circuit responsive to the operation of said second UNITED STATES PATENTS Hildebrand et a1. 55-139 X Hildebrand 55-104 Foley 55-104 Robinson et al 55-105 Robinson et al 55-105 relay member in said second circuit to operate said 10 ROBERT F BURNETT, Primary Examiner.

variable resistor in said first circuit. 

